1. Field of the Invention
This invention relates to a method and apparatus for tomographic touch imaging sensor and interactive system using same. More particularly, the invention relates to a method and apparatus for touch sensitive devices for computing systems or for controlling actions of associated devices or equipment, and still more particularly, to devices that detect and/or process simultaneously multiple touch interactions (by fingers or other objects) at distinct locations on a touch-sensitive surface.
2. Prior Related Art
Many types of input devices are presently available for performing operations in a computing system, such as buttons or keys, mice, trackballs, touch panels, joysticks, touch screens and the like. Touch screens, in particular, are becoming increasingly popular because of the ease and versatility of operation, as well as, their declining price. Touch screens can include a touch panel, which can be a clear panel with a touch-sensitive surface. The touch panel can be positioned in front of a display screen so that the touch-sensitive surface covers the viewable area of the display screen. Touch screens can allow a user to make selections and move a cursor by simply touching the display screen via a finger or stylus. In general, the touch screen can recognize the touch and position of the touch on the display screen, and the computing system can interpret the touch and thereafter perform an action based on the touch event.
One limitation of many conventional touch panel technologies is that they are only capable of reporting a single point or touch event, even when multiple objects simultaneously come into contact with the sensing surface. That is, they lack the ability to track multiple points of contact at the same time. Thus, even when two points are touched, these conventional devices can only identify a single location, which is typically the average between the two contacts (e.g. a conventional touchpad on a notebook computer provides such functionality). This single-point identification is a function of the way these devices provide a value representative of the touch point, which is generally by providing an average resistance or capacitance value.
Another limitation of most touch panels is that, besides being incapable of reporting a plurality of touch points that occurs simultaneously, is that they provide information about just touch coordinates. Most known touch panels cannot provide a complete representation of the details of all shapes contacting the panel, because the methods of detection often include just triangulation of touch points. Thus, a need exists for providing a better and fuller representation of touch interactions. The present invention proposes to provide a method and apparatus for achieving, for example, by providing a pixilated image representative of all the touch areas and their shapes. This ability of providing a full representation of all touch interactions is sometimes called “true-touch”.